This serves up the wrong file. Note the HIT to the cache, as well as the last-modified date being March 15. The ZIP downloaded here is an older version, 6.0.5.21 instead of an updated version made on the 29th. Downloading the ZIP through a browser, logged into the site, gives you the correct version.

This may also be interfering with download stats if the request is not passing through to the site.

Because this only happens to "anonymous" hits, WordPress sites likely cannot receive plugin updates at this time. They get the old ZIP files and thus don't get the new updates. Updates never work, they always show as being available for that plugin.